[Marv829]

Ok hear it is STOCK: (######) = HPI part numbers.

The pinion gear on the motor is a 20T(100919) which drives the spur gear which is a 44T(102093) for a ratio of: 44/20=2.200

That spur gear shaft(86089) has the next gear on it which is a 18T(86097) drive gear that drives a 44T(100905) idle gear on the idler shaft(100905) for a ratio of: 44/18=2.444

On that same idler shaft is the next gear a 32T(86084) drive gear that drives a 29T(86098) idle/output gear for a ratio of: 29/32=0.906

The output gear shaft(86081) then feeds power to the diffs via the drive shafts(86246). The drive shafts feed a 13T(102246b) bevel gear in the diff which drives a 43T(102246a) bevel gear for a ratio of: 43/13=3.307

Multiply 2.200 x 2.444 x 0.906 x 3.307 = 16.109

So the stock ratio is 16.109



(From other post)------Hi, I have the following:

Diffs @ 3.307 (43:13)
Trannny @ top drive gear to first idle gear 2.444 (44:18)
Trannny @ second idle gear to output gear 0.906 (29:32)
Spur-Pinion @ 2.200 (44: 20)

For a total ratio of 16.109

With 14.8v, 2200kv and 6.3" tire the math for that combo is ~37.9mph

Where our math differs is the second gearing stage of the tranny.
I see the 32T gear on the idle shaft driving the 29T gear on the output shaft. Which means it would only take the 32T gear 0.906 of a revolution to turn the 29T output gear one full revoultion.--------